Problem: Khan.scratchpad.disable(); Ishaan sells magazine subscriptions and earns $$5$ for every new subscriber he signs up. Ishaan also earns a $$21$ weekly bonus regardless of how many magazine subscriptions he sells. If Ishaan wants to earn at least $$81$ this week, what is the minimum number of subscriptions he needs to sell?
Solution: To solve this, let's set up an expression to show how much money Ishaan will make. Amount earned this week $=$ $ $ Subscriptions sold $\times$ Price per subscription $+$ Weekly bonus Since Ishaan wants to make at least $$81$ this week, we can turn this into an inequality. Amount earned this week $\geq $81$ Subscriptions sold $\times$ Price per subscription $+$ Weekly bonus $\geq $81$ We are solving for the number of subscriptions sold, so let subscriptions sold be represented by the variable $x$ We can now plug in: $x \cdot $5 + $21 \geq $81$ $ x \cdot $5 \geq $81 - $21 $ $ x \cdot $5 \geq $60 $ $x \geq \dfrac{60}{5} = 12$ Ishaan must sell at least 12 subscriptions this week.